A Frequency Modulated (FM) Transmitter typically utilizes an LC tank circuit coupled as a load. Due to the FM frequency range of 65 MHz˜108 MHz, it is not possible to implement both capacitor and inductor onto silicon die simultaneously. For practical silicon die area, only the capacitor is realized on-chip and made tunable for channels selection. An external inductor (L) is utilized (for example, L=120 nH) to form the required LC tank circuit. A flat gain response is desirable.
A FM transmitter maintaining a flat gain for a frequency range of interest is essential for several reasons. Some of those reasons are enumerated below:                For every dB increment in FM transmitter power, the Nth harmonic of the FM transmitter increases by N dB.        With a wide FM operating frequency range such as 65 MHz˜108 MHz, the harmonics level at the FM transmitter output become important. For example, on the higher end of FM frequency, the 9th harmonics fall inside a GSM band.        For the FM transmitter, the desired signal at 120 dBμV is to be delivered over the full frequency range of 65 MHz˜108 MHz. The corresponding harmonics that fall inside the cellular band must be at most −120 dBm (conducted) to avoid interfering with the cellular system.        If the gain of the FM transmitter is not flat, then to meet the desired signal level of 120 dBμV at 65 MHz will also result in higher output level at 108 MHz. And the corresponding cellular in-band harmonics will be compromised.        
However, if the FM transmitter gain is flat over the frequency range of interest the above identified issues can be minimized.
However, there are limitations in providing a FM transmitter with a flat gain over a wide frequency range when utilizing an external inductor (L). Some of the limitations are described below:                The Q of the external L varies across a wide operating frequency (for example, 65 MHz˜108 MHz)        The Q of the external L varies with manufacturers.        The frequency response of the external L itself varies greatly over frequency.        
With such external inductor characteristics, a flat gain response over 65 MHz<f<108 MHz is difficult to achieve without significantly affecting cost and potentially the size of the FM transmitter.
Accordingly, what is needed is a system and method that addresses the above-identified issue. The system and method should be adaptable, cost effective and easily implemented in existing transmitters. The present invention addresses such a need.